What model did — and you heard price is steep (8)
I believe the answer is:
saturate
'is steep' is the definition.
(I've seen this before)
'what model did and you heard price' is the wordplay.
'what model did' becomes 'sat' (to sit is to model - past tense).
'and' means one lot of letters go next to another.
'heard' shows a homophone (sound like).
'price' becomes 'rate' (I've seen this in another clue).
'you' is a homophone of 'u'.
'sat'+'u'+'rate'='SATURATE'
(Other definitions for saturate that I've seen before include "Drench thoroughly, soak" , "Soak completely" , "Make thoroughly wet, soak" , "flood" , "steep" .)